A hydraulic hammer, often referred to as a breaker, can be attached to various machines for the purpose of milling asphalt, concrete, stone, and other construction materials. A conventional hammer includes a work tool (e.g., a chisel) having a tip that engages the material to be milled, and a reciprocating piston that is moved by pressurized fluid to repetitively slam against a base end of the work tool. The pressurized fluid used to move the piston is supplied to the piston from a remote accumulator. One or more valves are located within long passages that extend between the accumulator and the piston to control fluid flow from the piston to the accumulator and from the accumulator to the piston.
Although perhaps suitable for some applications, conventional hammers suffer drawbacks. In particular, the passages that communicate the accumulator and piston, because of their lengths, may increase the time it takes for the fluid to travel between the piston and accumulator. This increased fluid travel time can result in a delayed response of the system. For example, a delay may occur between the times the system is activated and the piston is driven forward against the work tool, and likewise between the times the system is deactivated and the piston is withdrawn from the work tool. A delayed hammer response can reduce an overall productivity and efficiency of the machine.
One attempt to improve hammer operation is disclosed in U.S. Patent Publication No. 2014/0262406 of Moore that published on Sep. 18, 2014 (“the '406 publication”). In particular, the '406 publication discloses a hammer having a piston sleeve, in which a piston reciprocates. A sleeve liner is placed over the sleeve, and an accumulator membrane surrounds the sleeve liner. The piston is supplied with and drained of fluid by way of passages formed between the sleeve and the sleeve liner. Specifically, longitudinally extending slots are machined into an outer annular surface of the piston sleeve, and when the sleeve liner is placed over the piston sleeve, the slots become passages for transporting high-pressure fluid to and from the piston. Because the accumulator membrane is located around the sleeve and close to the piston, the fluid passages are short, allowing for enhanced system responsiveness.
The disclosed hammer is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.